This invention concerns a container closure which is both tamper resistant and tamper indicating. More specifically, this invention is directed to a closure for pressurized cans typically filled with materials, such as commercial food products, sold in retail stores. The goal of this invention is to inhibit or at least greatly discourage the unauthorized release of the gas, nitrous oxide, which propells the product from the can, and also to provide an especially visable indication if the closure prior to sale has been removed and remounted, or even if there has been a partial attempt to remove the closure.
Although the need for tamper indicating as well as for tamper discouraging closures for many types of consumer goods long has been recognized and generally well met, so as to ensure that the purchaser obtains a full container and there was no accidental or environmental product contamination, only recently there has arisen an urgent need for great improvement in both tamper indicating and tamper resistant closures, to prevent intentional tampering and/or contamination of the goods by individuals who wish to do bodily harm to the ultimate purchaser of the goods, or to cause financial hardship to the manufacturer of the goods, or to obtain some "feature" from the goods without purchase of a large quantity of the goods.
A specific example of a "feature", which recently has become a cause for human intentional tampering, is nitrous oxide. Nitrous oxide is employed in so-called "aerosol" cans for propelling foods and other substances through a valve assembly at the top of the can. Partial actuation of the valve assembly by tampering will permit escape of the nitrous oxide gas, without delivery of the goods, such as cream topping. An obvious result of withdrawing some or most of the nitrous oxide is that there will be insufficient gas in the can to propell most of the contents and, the ultimate purchaser has been cheated. However, the real concern lies in the fact that the nitrous oxide is being inhaled or "sniffed" intentionally by the tamperer, so as to obtain an exhilaration or "high". This concern is not based on morality, but is predicated upon public health and safety. Abuse of nitrous oxide has been associated with several serious diseases, disorders, or conditions. Also, exposure to nitrous oxide in high concentrations can result in asphyxiation. As with the abuse of drugs, alcohol, and other substances, the potential damage to the abuser, the sniffer, of nitrous oxide is of no concern to the sniffer. Nevertheless, it is incumbent upon the manufacturers and packagers of aerosol products to take steps to reduce the ease of nitrous oxide abuse by delivering the product in a more tamper resistant and/or tamper indicating package.